Information Assurance
Malicious Code

- Data loss
- Downtime
- Denial of service

Malicious code is a general term for programs written to damage or intrude on other systems. We presented one type of malicious code — the virus. There are also time bombs and logic bombs. These bombs activate based on time, or on a specific program event, or lack of an event.
Malicious code includes Trojan Horses and worms. A Trojan Horse is an apparently useful program that does more or less than a user expects, usually maliciously. For example, if one of your command files had been Trojanized, you might request a list of files in a directory, and receive a list of all the files...except those added by the hacker. You could download an apparently innocent game which will erase your hard drive while you are playing.
Worms have one purpose — to reproduce, and to find space to reproduce again, filling all available disk or memory space. Worms can also carry viruses as payloads, delivering unwanted gifts as they pile through systems and circuits. Malicious code today more often blurs distinctions, combining features of worms, viruses, and Trojan Horses.
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